public class MyLinkedList implements IList{
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;//链表的头
    public ListNode last;//链表的尾

    @Override
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            last = node;
        }else{
            node.next = head;
            head.prev = node;
            head = node;
        }
    }

    @Override
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            last = node;
        }else{
            last.next = node;
            node.prev = last;
            last = node;
        }
    }

    @Override
    public void addIndex(int index, int data) throws OutofIndex{
        int len = size();
        if(index<0 || index>len){
            throw new RuntimeException("双向链表位置不合法:"+index);
        }
        if(index == 0){
            addFirst(data);
            return;
        }
        if(index == len){
            addLast(data);
        }
        ListNode node = new ListNode(data);
        ListNode cur = findIndex(index);
        node.next = cur;
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
    }
    private ListNode findIndex(int index){
        ListNode cur = head;
        while(index != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    @Override
    public boolean contains(int key) {
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
                //删除头节点
                if(cur == head){
                    head = head.next;
                    if(head == null){
                        last = null;
                        return;
                    }
                    head.prev = null;
                }else{
                    //删除尾结点
                    if(cur == last){
                        last = last.prev;
                        last.next = null;
                    }else{
                        //删除中间节点
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }
                }
                return;
            }else{
                cur = cur.next;
            }
        }
    }

    @Override
    public void removeAllKey(int key) {
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
                //删除头节点
                if(cur == head){
                    head = head.next;
                    if(head == null){
                        last = null;
                        return;
                    }
                    head.prev = null;
                }else{
                    //删除尾结点
                    if(cur == last){
                        last = last.prev;
                        last.next = null;
                    }else{
                        //删除中间节点
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }

    @Override
    public int size() {
        int count = 0;
        ListNode cur = head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while(cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
    }

    @Override
    public void clear() {

    }
}
